Variable powered contact lens

Abstract

A soft contact lens of soft opthalmic plastic material with an anterior portion resiliently deformable by movement of the eye. The lens is of the scleral-corneal type, and has a base-down prism portion which moves under the lower eyelid. When the eye gazes downwardly and inwardly, pressure of the lower lid on the thickened portion of the lens causes a bulging of the anterior portion of the lens near the center, creating an increase in diopter power. A slab-off bevel of the lens sides shapes the bulge into proper spherical condition for clearer vision.

What is claimed is: 
     
       1. A contact lens for non-rotational, non-translational orientation in the eye of the wearer, comprising, a soft, resiliently deformable opthalmic plastic material lens;   said lens having a posterior surface conforming to the corneal surface of the wearer's eye and having a perimeter area extending upon the scleral surface of the wearer's eye;   said lens having a front surface with a radius adapted to correct distance vision of the wearer;   said lens having a base-down prism on the anterior surface, with a thickness such that pressure from the lower eyelid, when the eye gazes downwardly and inwardly, will cause the lens to resiliently deform to create a thickened bulge which reduces the radius of the lens near the center of the anterior surface;   said lens having a beveled edge on its temporal and nasal sides, said bevels being on the anterior surface of the lens adapted to form a uniform, spheric bulge when said bulge is formed;   said lens having a beveled lower edge on the posterior surface for a smoother fit within the lower fornix of the eye.   
     
     
       2. The contact lens of claim 1 wherein the lens material is a high water content gel, with an equalibriated water content of about 79%, and with a resiliently deformable anterior portion. 
     
     
       3. The contact lens of claim 1 wherein the temporal bevel is slightly wider in front elevational view than the nasal bevel. 
     
     
       4. The contact lens of claim 1, wherein the temporal and nasal bevels begin with a steep slope at points which are located spaced away from the center upper point of the lens, the slopes becoming shallower as the bevels widen in front elevational view, and becoming steeper again on the lower portion of the lens, said bevels ending at the lower center portion of the perimeter of the lens, the beginning points of the bevels being separated by a greater distance than the ending points of the bevels. 
     
     
       5. The contact lens of claim 1, wherein the posterior surface has a toric shape for wearers with high astigmatism. 
     
     
       6. The contact lens of claim 1, wherein the lens material is a very soft silicone material.